Are the <i>XYZ</i> states unconventional states or conventional states with unconventional properties?

Hanhart, C.; Klempt, E.

doi:10.1142/s0217751x20500190

Cited by 10 publications

(5 citation statements)

References 139 publications

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“…Thus, it is unclear which structure(s) can be identified as the candidate(s) of the D * D1(2) bound states. Nevertheless, the Y (4360), aka ψ(4360), and ψ(4415) have been suggested to correspond to the D 1 D * and D 2 D * states, respectively [171][172][173][174]. A determination of the poles around 4.4 GeV would require a thorough analysis of the full data sets including these open-charm channels, and the first steps have been done in Refs.…”

Section: ( * ) D( * )mentioning

confidence: 99%

A survey of heavy-antiheavy hadronic molecules

Dong,

Guo,

Zou

2021

Preprint

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Many efforts have been made to reveal the nature of the overabundant resonant structures observed by the worldwide experiments in the last two decades. Hadronic molecules attract special attention because many of these seemingly unconventional resonances are located close to the threshold of a pair of hadrons. To give an overall feature of the spectrum of hadronic molecules composed of a pair of heavy-antiheavy hadrons, namely, which pairs are possible to form molecular states, we take charmed hadrons for example to investigate the interaction between them and search for poles by solving the Bethe-Salpeter equation. We consider all possible combinations of hadron pairs of the S-wave singly-charmed mesons and baryons as well as the narrow P -wave charmed mesons. The interactions, which are assumed to be meson-exchange saturated, are described by constant contact terms which are resummed to generate poles. It turns out that if a system is attractive near threshold by the light meson exchange, there is a pole close to threshold corresponding to a bound state or a virtual state, depending on the strength of interaction and the cutoff. In total, 229 molecular states are predicted. The observed near-threshold structures with hidden-charm, like the famous X(3872) and Pc states, fit into the spectrum we obtain. We also highlight a Λc Λc bound state that has a pole consistent with the cross section of the e + e − → Λc Λc precisely measured by the BESIII Collaboration.

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Section: ( * ) D( * )mentioning

confidence: 99%

A survey of heavy-antiheavy hadronic molecules

Dong,

Guo,

Zou

2021

Preprint

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“…This state is by itself quite interesting since it apparently does not fit into the spectrum of vector charmonia predicted by various quark models, although some adjustment of the models might improve the situation -see the related discussion in Ref. [32]. One exotic proposal for this state is a hadrocharmonium structure [33], where a compact ψ(2S) core is surrounded by excited light quarks, which at the same time qualifies as a f 0 (980)ψ(2S) hadronic molecule due to the proximity of the corresponding threshold [34].…”

Section: Introductionmentioning

confidence: 99%

Is $Z_{cs}(3982)$ a molecular partner of $Z_c(3900)$ and $Z_c(4020)$ states?

Baru,

Epelbaum,

Filin

et al. 2021

Preprint

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We perform an effective-field-theory-based coupled-channel analysis of the recent BES III data on the e + e − annihilation into the final state) in a wide energy range and extract the poles responsible for the formation of the Z cs (3982). We identify two scenarios which provide a similar description of the experimental mass distributions but result in utterly different predictions for the spin partners of the Z cs (3982): although both scenarios are consistent with the Z cs as a SU (3) partner of the Z c (3900), the Z c (4020) appears naturally as a spin partner of these states only in one of them (fit 1) while in the other (fit 2) its nature has to be different. Also, the Z cs (3982) has a J P = 1 + spin partner near the D * s D * threshold in fit 1, while no such state exists in fit 2. We predict the D * s D * invariant mass distribution in the J P = 1 + channel for the reaction e + e − → K + D * − s D * 0 and argue that this line shape can be used to distinguish between the two scenarios once data in this channel are available.

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“…The spectroscopy of charmonia [31] and bottomonia [32,33] in e + e − and pp or pp collisions is a well-established research field. The spectra have been measured in great detail, and most of the excited spin-singlet (η c (nS), η b (nS)) and spin-triplet (J/ψ(1S), ψ(nS), χ c (nP ); Υ(nS), χ b (nP )) states as well as their hadronic and other decay modes have been resolved [34].…”

Section: Model Ingredientsmentioning

confidence: 99%

Bottomonium spectroscopy in the quark-gluon plasma

Wolschin

2020

Preprint

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The spectroscopic properties of heavy quarkonia are substantially different in the quark-gluon plasma (QGP) that is created in relativistic heavy-ion collisions as compared to the vacuum situation that can be tested in pp collisions at the same center-of-mass energy. In this article, a series of recent works about the dissociation of the Υ(nS) and χ b (nP ) states in the hot QGP is summarized. Quarkonia dissociation occurs due to (1) screening of the real quark-antiquark potential, (2) collisional damping through the imaginary part of the potential, and (3) gluon-induced dissociation. In addition, reduced feed-down plays a decisive role for the spin-triplet ground state. Transverse-momentum and centrality-dependent data are well reproduced in Pb-Pb collisions at LHC energies. In the asymmetric p-Pb system, alterations of the parton density functions in the lead nucleus account for the leading fraction of the modifications in cold nuclear matter (CNM), but the hot-medium effects turn out to be relevant in spite of the small initial spatial extent of the fireball, providing additional evidence for the generation of a quark-gluon droplet.

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Are the XYZ states unconventional states or conventional states with unconventional properties?

Cited by 10 publications

References 139 publications

A survey of heavy-antiheavy hadronic molecules

A survey of heavy-antiheavy hadronic molecules

Is $Z_{cs}(3982)$ a molecular partner of $Z_c(3900)$ and $Z_c(4020)$ states?

Bottomonium spectroscopy in the quark-gluon plasma

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